This research continues the earlier researches on wear
friction and lubrication and its application to the powder
metallurgy industries. A detailed study of the parameters
involved in wear and friction has been made by using the "Pin
and Disc" machine with cross cylinders technique. One iron
powder was chosen and compacted over a range of densities with
a series of metallic stearates as admixed lubricants for the
purpose of examinations. These compacts were used as the "pins"
for the wear and friction apparatus, the "disc" was made from
high carbon high chromium steel which is one of the steels
normally used in punches and dies in the powder metallurgy
industries. The wear behaviour of these compacts was studied in
relation to the following parameters: applied load between
compact (or pin) and disc, sliding speed, travelled distance,
density and hardness of compact. These were examined for a range
of stearate lubricants and the wear rates determined, these data
were then related to the possible industrial life for punches
and dies in powder metallurgy presses.
Besides wear rate, friction forces between the compact (or
pin) and disc were measured and these forces of friction were translated
into coefficients of friction for each type of lubricant.
The thesis presents the results of these investigations with
a survey of current theories on wear and friction of metallic
systems relevant to powder metallurgy. Conclusions have been drawn and suggestions made on the most useful solid lubricant necessary
in the pressing of metallic powders to reduce wear and friction in
production presses. Calculations have been carried out using the
data collected to estimate the possible press tool wear and
accordingly a possible tool life was determined for pressing
with each type of ~tearate lubricant. The overall conclusion was
that zinc stearate is the best solid lubricant in the five metallic
stearates (Al, Na, Mg, Ca and Zn) for use in iron powder
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.